How to rotate textures? Or how to set texture coordinates?
You can use "Mapping" node: with this node you can edit scale, location and rotation of your texture. Just add it to the node tree of your shader and connect the "Vector" output to the "Vector" socket of your image nodes (try only mask first, and if it doesn't work try with both mask and color/rgh/nrm maps). "Mapping" node needs the "Texture coordinate" node (Shift+A > Input > Texture coordinate). 

But I would suggest to properly UV unwrap your plane, so the direction is set in the UV editor once: